This paper evaluates the historical development of national park policy and administration in Japan from the perspective of achieving sustainable development in nationally important ecological areas. Contrary to the widely held belief, the national park system in Japan has been unsuccessful in balancing conservation and development. The fundamental reasons for its failure are as follows: the Japan`s national park system has been largely founded and developed based on economic grounds and held sway by economic development policy; the policy and administrative coordination between government units concerning conservation and development has not been carried out; public participation and environmental groups` involvement in the decision making have been extremely limited; national parks have been perceived in the public image not as distinctive national heritage but as finest and popular tourist sites; and the dominant interest of tourism and recreational development has prevailed over conservation interest. Japan`s unsuccessful experience and lessons imply that there is urgent need to drastically reform our national park system, largely founded on the Japanese model, in order to save our last national environmental heritage.